A known seat slide apparatus for a vehicle is disclosed in JP2006-298104A, which is hereinbelow referred to as reference 1. The seat slide apparatus disclosed in the reference 1 includes a lower rail and an upper rail. The lower rail is secured to a vehicle floor. The upper rail is secured to a vehicle seat and movably supported relative to the lower rail. A bent portion is provided at an intermediate portion of the longitudinal direction of the lower rail. The bent portion is formed by cutting and upwardly bending a bottom portion of the lower rail in an inclined manner. On the other hand, first and second bent portions are provided at front and rear ends of the upper rail, respectively. The first and second bent portions are formed by cutting and downwardly bending a sidewall portion of the upper rail in an inclined manner. A side surface of the first bent portion of the upper rail and one side surface of the bent portion of the lower rail are arranged to face each other in a moving direction of the upper rail and to partly make contact with each other. In the same manner, a side surface of the second bent portion of the upper rail and another side surface of the bent portion of the lower rail are arranged to face each other in a moving direction of the upper rail and to partly make contact with each other. In accordance with a sliding movement of the upper rail, the first and second bent portions of the upper rail engage with the bent portion of lower rail in order to restrict a moving distance of the upper rail relative to the lower rail.
According to the seat slide apparatus for a vehicle disclosed in the reference 1, the upper and lower rails are assembled to each other so as to be relatively movable before forming the bent portion of the lower rail, for example. In such a state, the bent portion of the lower rail is formed between the first and second bent portions of the upper rail. In this case, when forming the bent portion of the lower rail, the upper rail interferes with the bent portion of the lower rail therefore preventing the bent portion of the lower rail from being bent sufficiently. Specifically, the lower rail made of metal may not be bent sufficiently because of a springback effect when forming the bent portion of the lower rail. Therefore, sufficient degree of engagement between each of the first and second bent portions of the upper rail and the bent portion of the lower rail may not be obtained, thereby a moving distance of the upper rail relative to the lower rail may not be surely restricted.
On the other hand, when the bent portion of the lower rail is bent excessively in order to obtain the sufficient degree of the engagement, the upper rail may receive a load generated when forming the bent portion of the lower rail. In such a case, dimensional accuracy may decrease, which may cause the upper and lower rails not to be movable relative to each other.
A need thus exists for a seat slide apparatus for a vehicle, which is not susceptible to the drawback mentioned above.